1. Field of the Invention
The present invention generally relates to an image processing system or apparatus designed to interface with different monitors apparatus, and more particularly to an image processing apparatus which processes image data to thereby display an image on screens of a color display unit and a monochromatic display unit such as a CRT display unit.
2. Prior Art
Conventionally, the image processing apparatus (so called CRT) is well known for displaying a certain image on the screen of CRT display unit under a control of a central processing unit (CPU). In such image processing apparatus, predetermined registers pre-store a timing for generating a horizontal or vertical synchronizing signal, a frequency of a dot clock pulse and a start address for reading data from a video random access memory (VRAM). Thus, the image processing apparatus performs a display control in response to the data stored in these registers.
Meanwhile, the image processing apparatus must use different initialization data such as data representative of the timing for generating synchronizing signals, data representative of the frequency of the dot clock pulse and other data based on kinds of connected monitor. More specifically, the above initialization data must be different for a color monitor and a monochromatic monitor. Such difference of initialization data is caused by a difference between general standards of the color monitor and the monochromatic monitor.
In the case where programs of the CPU are written for the color monitor and such programs are used for controlling the image processing apparatus to thereby display the image on the screen of the monochromatic monitor, data stored in the registers of the image processing apparatus must be set for the color display because of an initialization process. In such case, the conventional image processing apparatus suffers several kinds of disadvantages due to a difference between programs for the color display and the monochromatic display.
In the above-mentioned case, the programs must be rewritten so as to rewrite the data values of the registers for the color monitor to other data values of the registers for the monochromatic monitor. More specifically, the programs having the same function must be written independently for use in the color monitor and the monochromatic monitor. Hence, the conventional image processing apparatus suffers disadvantages in that a design of software must be troublesome and the designed programs can not be used generally. The above disadvantages (or problems) must be dealt with when the conventional apparatus is used for both of the color monitor and the monochromatic monitor. In addition, such disadvantages must be also dealt with when the conventional apparatus is used for color monitors having different standards and when the conventional apparatus is used for monochromatic monitors having different standards.